Although they are getting gray, most Americans want to be green. A capacious color, green conveys multiple and mutually contradictory meanings. Green is the color of money; plants, grass, meadows, and mountains; and youth, uncorrupted by experience. It also indicates envy; a pale and sickly appearance; and guardians of endangered species and ecosystems. Green says go: It doesn't say where. In the United States, where gray is dull, dreary, and decrepit, an uncivil war pits one green party against another -- spenders versus stewards. At stake, some say, is the future of the nation, and life as we know it.

The subject can weigh you down; it can make you blue. Skeptical about growth, deregulation, privatization, commercialization, and quick technological fixes, Ted Steinberg, Judith Levine, and Muriel Gillick are guardian greens. They can be preachy. But they are not ponderous. Their accounts of mundane activities -- mowing, shopping, aging -- are stocked with suggestive stories and statistics and a good deal of practical good sense about individual and collective responsibility, consumerism, and citizenship, and distinctions between need and desire.

The ''quest for the perfect lawn" is an American obsession, according to Steinberg, an environmental historian at Case Western Reserve University. Markers of class privilege since the 18th century, lawns began to appear adjacent to homes in the 1860s. Stimulated by the development and marketing of Turf Builder, Weed and Feed, and power mowers, lawn care ranked ''with orthodontia as one of the foremost suburban sciences" by the 1950s, he writes, with homeowners in Levittown, N.Y., required to mow their lawns at least once a week between April and November. With 40 million acres of turf in place by the 21st century, on 58 million residences, 15,000 golf courses, and 250,000 backyard putting greens, maintenance has become a multibillion-dollar business.

Perfection exacts a price, of course, and Steinberg's ''American Green" takes a long walk on the dark side. Power mowers have turned yards into ''toe away" zones. In 2003, at least 84,000 injuries occurred, many of them from projectiles fired with the force of a .357 Magnum, according to Steinberg. Even more ominous is the environmental impact of pesticides and fertilizers, and the millions of gallons of gasoline used on noise-polluting mowers and leaf blowers. Steinberg savages the health and safety claims of the lawn care industry. Companies boast that photosynthesis generates oxygen for the planet. They do not acknowledge that forests do it more efficiently or that oxygen is not in short supply anywhere on earth. In 1988, Robert Abrams, attorney general of New York State, sued ChemLawn for claiming that ''a child would have to swallow the amount of pesticide found in almost 10 cups of treated lawn clippings to equal the toxicity of one baby aspirin."

ChemLawn settled, but the industry has beaten back most attempts at regulation by the government. Although racing riding mowers has become the ''poor man's NASCAR," there are no safety standards for vehicles like Geronimow, which are prone to tip over. A blade stop feature has been designed, but is not mandated for mowers. Thirty-nine states prohibit cities and towns from regulating pesticides. The Environmental Protection Agency, according to Steinberg, tests pesticides singly but not in combination; permits some pesticides that cannot be sprayed on foods to be used on lawns; has not evaluated some popular products, including 2,4-D, mecoprop, and dicamba; and does not require manufacturers to enumerate health risks on packaging. Ironite was banned in Canada in 1997, but fertilizers are subject to virtually no regulation in the United States.

Government, Steinberg concludes, is not likely to intervene anytime soon. And the Citizens Against Lawn Mower Madness has not generated a push-mower revival. Steinberg thinks a landscape revolution might come in the Southwest, where water is scarce and xeriscaping, with drought-resistant vegetation, is catching on. In the meantime, Americans should leave the clippings on the lawn, mow higher, zap the weeds a lot less frequently -- and begin to believe that brown is beautiful.

Like Steinberg, Levine, author of ''Not Buying It," worries about ''human profligacy with nature's bounty" in a nation that consumes 24 percent of the world's resources. She, too, is not inclined to investigate possible economic benefits of consumption. A 50-something freelance writer, Levine and her significant other divide their time between Hardwick, Vt., and Brooklyn, N.Y. A vegetarian and inveterate Bush-basher, she discharged her bile at ''the consumer in chief," whose policies, she believes, will put baby boomers ''out on ice floes," by embarking on an experiment in voluntary simplicity. During 2004, she vowed to purchase only necessities: no processed or prepared foods, restaurant meals, clothing, movie tickets, video rentals, or gifts.

Levine's model was Henry David Thoreau. Acknowledging that her abstention would have no impact on consumer culture, she hoped to return with a better understanding of herself and ''the non-purchase decision." It wasn't easy. She missed the tastes and smells of street foods, and conversations with friends about the latest films. And she cheated, more than once, purchasing SmartWool socks and then greenish jacquard silk-polyester pants. But she stuck it out, making a valentine from a matchbox, honing her skills at Scrabble, and habituating public libraries and museums. In June, she paid off a $7,956.21 credit card debt. By October, she reclaimed her bohemian identity: ''counterculturalist to the culture of the counter."

Levine discovered that the line dividing wants and needs is thin and subjective. Why are vegetables essential and flowers, food for the soul, a luxury? What about two residences, three cars, political contributions to MoveOn, and flights to Montana for a niece's graduation?

Nor did she ever figure out why people buy -- or decide not to. Does consuming confer pleasure and power? Does not buying make us feel vulnerable and in need of help? Levine doesn't want to discourage girls from desiring frivolous shoes because they might then ''give up the sexy dream of dancing the night away." Can't they have the dream -- and the dance -- without the shoes?

Levine believes, fervently, that Americans should take back their identities as citizens as well as consumers, and stop the starvation of public transportation, libraries, and schools: Unlike the ''stagnant exchange of the marketplace, dollar for product[, the] price of democracy is eternal haggling. . . . And all the while, it must be owned and used by everyone." But she seems uncertain about how to bring about change: Is anti-consumption ''the Puritanism of the Left," or is it a viable strategy for political change?

Convinced, perhaps, that the time for collective action has not come, Levine concludes with a Thoreauvian paean to personal responsibility. Americans need to learn, as she did, that enough can be as good as a feast -- and how to assuage transient needs without consuming. Levine spent $8,000 less in 2004 than in 2003 and did not bicker with her partner over money. Since ''consciousness tugs at the sleeve of personal responsibility," she hopes her readers will become mindful, each time they stroll to the store, that every purchase has an impact on the world's resources and people.

As they purchase statins, StairMasters, screenings for PSA levels, mammograms, and long-term health insurance, Americans seem determined to shop so they won't drop. By eating right and exercising, they believe they can go directly from active middle age to death (in their sleep). It rarely works that way. By 2050 about 19 million of us will get frail, go to hospitals and nursing homes, and use end-of-life technology, overtaxing a health care system that is already on life support.

It is neither wise nor practical to try to prolong every life at any cost, Muriel Gillick argues, provocatively and persuasively, in ''The Denial of Aging." A physician and professor at Harvard Medical School, Gillick believes that doctors, health care providers, and government policies should seek to enhance the quality of life for seniors, and forgo some tests and procedures that might -- or might not -- keep the grim reaper at bay for just a little longer. Hospice has the right idea: Keep terminally ill patients free of pain and help them from becoming a burden on loved ones.

Although hospitals are often toxic for older people, Gillick points out, Medicare pays for diagnostic tests, aggressive treatments, intravenous therapy, and feeding tubes, but not intermediate or palliative care. Since more than one-third of Americans over 65 fall each year, why not deem tai chi classes to improve balance and fitted hip protectors ''medically necessary"? Why not help seniors retain a modicum of control over their lives and combat social isolation (goals out of favor with risk-averse hospitals and nursing homes) by providing incentives for children to care for a parent, or for group homes with round-the-clock care?

''The Denial of Aging" is awash in suggestions for reform: Medicare should give more latitude to patients, physicians, and families to decide on treatment. The government should offer three benefits plans, for the robust, the frail, and the dying, with an option to switch -- and reimburse only acceptable end-of-life treatments. Medicare discounts on prescription drugs should go to seniors who accumulate ''Prolific Peddling Points," or miles in a club for walkers. Assisted-living facilities should be regulated and monitored. Some of her suggestions, if implemented, may give too much discretion to physicians and family members in the treatment of the frail and demented. Some require more government regulation, and some less. Some may save money and others, no doubt, will cost more. But Gillick is right: It's time to rethink health care in America. ''A good old age is within our grasp," she concludes, but, as she no doubt knows, it will take an exercise of our collective will not yet in evidence.

But then again, individuals and societies will do just about anything to avoid redirecting desire, rewarding denial, or dealing with death. That's why, as Kermit the Frog keeps reminding us, ''it's not that easy bein' green." And even tougher when you're gray.